This invention pertains to apparatus for controlling the activation and deactivation of equipment for cooling air.
In a further respect, the invention pertains to apparatus for preventing the cycling on and off of air conditioning apparatus set to be activated at a selected temperature.
In another respect, the invention pertains to apparatus of the type described which determines when to activate air conditioning equipment by comparing short term and long term ambient air temperatures.
In still a further respect, the invention pertains to apparatus of the type described which reduces the power consumption require to operate the equipment.
The utilization of compressor-driven and evaporative-cooler driven air conditioning equipment is well known in the art. One kind of evaporative cooler equipment is set forth in U.S. Pat. Nos. 4,443,387 and 4,693,852. These patents describe evaporative cooler equipment for maintaining a relatively constant ambient air temperature around dairy cows. The evaporative cooling equipment includes a plurality of spray nozzles and a fan which directs an air flow with water mist emitted from the nozzles toward the cows. The equipment also includes a control unit which activates the equipment when the ambient air temperature reaches a selected control temperature in the morning (or other time of day) and which deactivates the equipment when the ambient air temperatures falls to an associated control temperature in the afternoon (or other time of day).
While such evaporative cooling equipment has long been successfully used to maintain a selected ambient temperature around cows, one long standing xe2x80x9ccyclingxe2x80x9d problem associated with the equipment occurs when the equipment is activated in the morning and deactivated in the afternoon and evening. The equipment is activated in the morning and deactivated in the evening because the night time ambient air temperatures are low enough that evaporative cooling is not required. The cycling problem consists of the tendency of the equipment to xe2x80x9chuntxe2x80x9d or xe2x80x9csearchxe2x80x9d for the appropriate selected control temperature due to small variations in ambient air temperature when the equipment is turned on or off. For example, if the evaporative cooling equipment is set to be activated at a selected xe2x80x9cturn-onxe2x80x9d control temperature of 80xc2x0 F., the controller turns on the equipment when sensors monitored by the controller sense a temperature of 80xc2x0 F. If, however, the sensors within a few minutes then sense a temperature of 76xc2x0 F. (or less) then the controller turns off the equipment (assuming that the equipment is set with a hysteresis of 3 degrees F or less).
As soon as the sensors again detect an ambient air temperature of 80xc2x0 F., the controller again turns on the equipment. Ambient air temperatures can vary due to changes in the humidity, to breezes, to clouds moving over the sun, etc. Another reason is that as soon as the fans turn on, there is typically a drop in air temperature due to the increased air circulation and movement. This cycling on and off can occur even if the controller is programmed with a few degrees of hysteresis.
It is particularly important to keep the equipment operational for as long as necessary prior to turning the equipment off in the afternoon. If the selected turn-off control temperature is 76xc2x0 F., then when the temperature when taken each minute goes 76xc2x0-75xc2x0-76xc2x0-75xc2x0-76xc2x0-76xc2x0-76xc2x0-76xc2x0-77xc2x0-77xc2x0-76xc2x0-77xc2x0-76xc2x0-76xc2x0-77xc2x0-76xc2x0-75xc2x0-75xc2x0-76xc2x0-75xc2x0-75xc2x0-75xc2x0-75xc2x0-74xc2x0 F., it is desirable to not have the simply because a temperature of 75xc2x0 or 76xc2x0 F. is sensed.
Another problem associated with prior art evaporative cooling apparatus of the type described is that such apparatus initially utilized a one-half horsepower motor to power the fan. Customers often now demand a five horsepower or larger motor. Consequently, the cost of electricity has become an issue.
Accordingly, it would be highly desirable to provide improved evaporative cooling apparatus which would avoid cycling when the apparatus is turned on, and avoid prolonged operation when it is time to shut down the equipment.
Therefore, it is a principal object of the invention to provide improved air conditioning apparatus.
A further object of the instant invention is to provide improved evaporative cooling apparatus which avoids or minimizes xe2x80x9con-offxe2x80x9d cycling when the apparatus is being turned on or off at selected ambient air temperatures.
Another object of the invention is to provide improved evaporative cooling apparatus which reduces the cost of electricity required to power the apparatus.